Function: addhelp
Section: programming/specific
C-Name: addhelp
Prototype: vrs
Help: addhelp(sym,str): add/change help message for the symbol sym.
Doc: changes the help message for the symbol \kbd{sym}. The string \var{str} is
 expanded on the spot and stored as the online help for \kbd{sym}. If \kbd{sym}
 is a function \emph{you} have defined, its definition will still be printed
 before the message \var{str}.  It is recommended that you document global
 variables and user functions in this way. Of course \kbd{gp} will not protest
 if you skip this.  It is possible to attach a help text to an alias, but it
 will never be shown: aliases are expanded by the \kbd{?} help operator and we
 get the help of the functions the alias points to.

 Nothing prevents you from modifying the help of built-in PARI
 functions. But if you do, we would like to hear why you needed to do it!
